Acrylic matt thermoplastic resin films and process for producing the same

ABSTRACT

Acrylic matt thermoplastic resin films having excellent printability, flex whitening resistance, impact resistance and solvent resistance, and a process for the preparation thereof are provided. The films made of a thermoplastic resin composition comprising 100 parts by weight of an acrylic resin (A) and 0.5 to 20 parts by weight of a crosslinked acrylic polymer (B) as a matting agent are prepared by a process wherein the resin composition is kneaded and formed into a film, and the both surfaces of the film are simultaneously brought into contact with rolls between them, one roll being kept at a temperature of not less than the glass transition temperature Tg of the resin composition and the other roll being kept at a temperature of less than the Tg, whereby the film surface contacted with the roll having a temperature of Tg or higher is converted into a mirror surface and the film surface contacted with the roll having a temperature lower than Tg is converted into a matt surface.

TECHNICAL FIELD

The present invention relates to a matt thermoplastic resin filmsuitable for printing. More particularly, the invention relates to amatt acrylic thermoplastic resin film which has an excellentprintability and can be thermally processed without impairing lowglossiness, and a process for producing the matt film.

BACKGROUND ART

Moldings of thermoplastic resins such as acrylic resin generally havegloss (luster), and the gloss is an important property for some uses. Onthe other hand, there are also many uses that do not require gloss orprefer to be not glossy. In particular, matt moldings are preferred foruses such as interior materials for vehicles, furniture, housing ofelectric equipment, wallpapers and building materials.

Conventional processes for matting thermoplastic resins are roughlyclassified into (1) a process by embossing or by mechanical or chemicalmatting processing, and (2) a process by addition of an inorganic ororganic matting agent.

The process (1) has the advantage that in general decrease in physicalproperties is small, but has the problems that in addition to lowproductivity and increase in processing cost, the matting effect is notsufficient and, in many cases, gloss is restored if films are heated insecondary processing, thus the matting effect is lost. On the otherhand, the process (2) has the advantages that the productivity does notdecrease so much, it is easy to control the matting degree and theproducts are also applicable to uses wherein the products are subjectedto secondary processing, but has a large problem of decrease in physicalproperties. In particular, in case of using an inorganic material suchas silica gel as a matting agent, decrease in physical properties suchas impact resistance, tensile strength, elongation and transparency ismarked.

Also, in case of making a print on the surface of acrylic resin films,the process (2) has the problem that printing defect may occur due toprotrusions (hereinafter referred to as “fish eye”) on the surfaceresulting from foreign matter. With regard to transparent films, it isknown for solving the printing defect problem to bring the both surfacesof a film to contact with rolls kept at a temperature higher than Tg ofthe film. However, this method has the problem for matt films that thematt surface gets back to gloss surface. In JP-A-03-237134 is proposed amethod by incorporation of an organic matting agent, but in case ofmaking a print onto films, this method has the problems that sinceunevenness of the film surface is large, ink is hard to transfer ontoconcave portions, so no sharp printed pattern is obtained, or printingdefect takes place at protrusions on the film surface.

It is an object of the present invention to solve the above-mentionedproblems and to provide a matt acrylic thermoplastic resin film, withoutimpairing physical properties such as matting property, impactresistance, heat resistance, tensile strength and elongation, which isimproved so as to prevent the printing defect from occurring as much aspossible by decreasing protrusions on the film surface, and is improved,besides improvement in ink receptivity, so as to maintain a lowglossiness of one surface, and further which is hard to get back togloss surface even if subjected to secondary processing.

DISCLOSURE OF INVENTION

The present inventors have found that an acrylic matt film having anexcellent printability and secondarily processable without impairing thematting effect can be obtained by, when forming a film from athermoplastic resin composition wherein a crosslinked acrylic polymer isincorporated as a matting agent into an acrylic resin, bringing onesurface of the film into contact with a roll kept at a temperature ofnot less than the glass transition temperature (Tg) of the thermoplasticresin composition and simultaneously bringing the other surface of thefilm into contact with a roll kept at a temperature of less than the Tg,thereby converting the one surface into a mirror surface and convertingthe other surface into a matt surface, while the temperature of the filmis not less than the Tg of the thermoplastic resin composition.

Thus, the present invention provides a process for producing an acrylicmatt thermoplastic resin film comprising kneading a thermoplastic resincomposition comprising (A) 100 parts by weight of an acrylic resin and(B) 0.5 to 20 parts by weight of a crosslinked acrylic polymer as amatting agent, forming the composition into a film, and bringing theboth surfaces of the film into contact with rolls simultaneously betweenthe rolls, wherein one surface of the film is brought into contact witha roll kept at a temperature of not less than the glass transitiontemperature (Tg) of the resin composition (I) to thereby provide thesurface of the film with a mirror surface and the other surface of thefilm is brought into contact with a roll kept at a temperature of lessthan the Tg to thereby provide the other surface with a matt surface.

The films of the present invention can maintain a desirable low glosseven if subjected to secondary processing, since the increase in 60°reflectivity (%) of the matt surface by heating at 200° C. for 1 minuteis 10% or less.

The present invention also provides an acrylic matt thermoplastic resinfilm having a mirror surface on one surface and a matt surface on theother surface.

The thickness of the films of the present invention is usually from 10to 300 μm.

It is preferable that the crosslinked acrylic polymer (B) used formatting has a weight average particle size of 0.5 to 15 μm.

As acrylic resin (A) is preferably used an acrylic graft copolymercomprising (a-1) 5 to 85 parts by weight of at least one layer of anelastomeric polymer of 50 to 99.9% by weight of an alkyl acrylate, 0 to49.9% by weight of other copolymerizable vinyl monomer and 0.1 to 10% byweight of a copolymerizable polyfunctional monomer having at least twonon-conjugated double bonds per a molecule, and (a-2) 95 to 15 parts byweight of at least one layer of a graft component composed of 50 to 100%by weight of an alkyl methacrylate and 0 to 50% by weight of other vinylmonomer copolymerizable therewith which have been graft-copolymerizedonto the elastomeric polymer (a-1). It is preferable that the particlesize of the elastomeric polymer (a-1) is from 50 to 400 nm.

As crosslinked acrylic polymer (B) used for matting is preferably used anon-graft or graft copolymer comprising (b-1) 40 to 100 parts by weightof at least one layer of a crosslinked acrylic ester polymer prepared bypolymerizing 100 to 90% by weight of an acrylic monomer composed of 40to 90% by weight of an alkyl acrylate and 60 to 10% by weight of analkyl methacrylate with 0 to 10% by weight of at least one othercopolymerizable vinyl monomer and 0.1 to 20 parts by weight of acopolymerizable polyfunctional monomer having at least twonon-conjugated double bonds per a molecule based on 100 parts by weightof the total of the acrylic monomer and other vinyl monomer, and (b-2)60 to 0 part by weight of at least one layer of a graft componentcomposed of 60 to 100% by weight of an alkyl methacrylate, 0 to 40% byweight of an alkyl acrylate and 0 to 10% by weight of othercopolymerizable vinyl monomer which have been graft-copolymerized ontothe crosslinked acrylic ester polymer (b-1).

BEST MODE FOR CARRYING OUT THE INVENTION

The thermoplastic resin composition (I) used for the preparation of thefilms of the present invention comprises the acrylic resin (A) and 0.5to 20 parts by weight of the crosslinked acrylic polymer (B) for mattingper 100 parts by weight of the acrylic resin (A).

In the present invention, as the acrylic resin (A) is used an acrylicgraft copolymer obtained by polymerizing a vinyl monomer, especially avinyl monomer containing a predominant amount of an alkyl methacrylate,in the presence of an acrylic elastomer, especially a crosslinked alkylacrylate elastomeric homopolymer or copolymer.

Preferably, the acrylic resin (A) is an acrylic graft copolymer obtainedby polymerizing (a-2) 95 to 15 parts by weight of a graft componentcomposed of 50 to 100% by weight of an alkyl methacrylate and 0 to 50%by weight of other vinyl monomer copolymerizable therewith in thepresence of (a-1) 5 to 85 parts by weight of an elastomeric polymercomposed of 50 to 99.9% by weight of an alkyl acrylate, 0 to 49.9% byweight of other copolymerizable vinyl monomer and 0.1 to 10% by weightof a copolymerizable polyfunctional monomer having at least twonon-conjugated double bonds per a molecule (the total of the elastomericpolymer (a-1) and the graft component (a-2) being 100 parts by weight).The elastomeric polymer (a-1) may have a single layer structure or amulti-layer structure. It is preferable that the average particle sizeof the elastomeric polymer (a-1) is from 50 to 400 nm.

The alkyl acrylates used in the elastomeric polymer (a-1) are preferablythose having a C₁ to C₈ alkyl group, e.g., methyl acrylate, ethylacrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate,n-octyl acrylate, and the like. These may be used alone or in admixturethereof. The alkyl group of the alkyl acrylate may be linear or may bebranched, but if the number of carbon atoms thereof is more than 8, thereaction rate becomes slow. The content of the alkyl acryalte in theelastomeric polymer (a-1) is from 50 to 99.9% by weight, preferably 60to 99% by weight, more preferably 70 to 95% by weight. If the content ofthe alkyl acrylate is less than 50% by weight, the impact resistancelowers, and if the content is more than 99.9% by weight, thetransparency of films lowers.

The polyfunctional monomer having at least two non-conjugated doublebonds per a molecule used in the elastomeric polymer (a-1) is acomponent used as a crosslinking agent or a graftlinking agent. Examplesthereof are, for instance, a dialkylene glycol dimethacrylate such asethylene glycol dimethacrylate, diethylene glycol dimethacrylate,dipropylene glycol dimethacrylate or dibutylene glycol dimethacrylate, adialkylene glycol diacrylate such as those exemplified for thedialkylene glycol dimethacrylate wherein the dimethacrylate is replacedwith diacrylate, a vinyl group-containing polyfunctional monomer such asdivinyl benzene or divinyl adipate, an allyl group-containingpolyfunctional monomer such as diallyl phthalate, diallyl maleate, allylacrylate, allyl methacrylate, triallyl cyanurate or triallylisocyanurate, and the like. These may be used alone or in admixturethereof. The content of the polyfunctional monomer in the elastomericpolymer (a-1) is from 0.1 to 10% by weight, preferably 0.5 to 8% byweight, more preferably 0.7 to 5% by weight. If the content of thepolyfunctional monomer is less than 0.1% by weight, the solventresistance of films lowers, and if the content is more than 10% byweight, the elongation and impact resistance of films lower.

Examples of the other copolymerizable vinyl monomer used in theelastomeric polymer (a-1) are, for instance, an alkyl methacrylatehaving a C₁ to C₁₂ alkyl group such as methyl methacrylate, ethylmethacrylate, propyl methacrylate or butyl methacrylate, a hydroxyalkyl(meth)acrylate such as hydroxyethyl (meth)acrylate, glycidyl(meth)acrylate, an unsaturated carboxylic acid such as acrylic acid,methacrylic acid or crotonic acid, an aromatic vinyl compound such asstyrene, α-methylstyrene, o-, m- or p-methylstyrene or chlorostyrene, avinyl cyanide compound such as acrylonitrile or methacrylonitrile, ahalogenated vinyl compound such as vinyl chloride or vinylidenechloride, and the like. Alkyl methacrylates are preferable. The contentof the other vinyl monomer in the elastomeric polymer (a-1) is from 0 to49.9% by weight, preferably 5 to 45% by weight.

The elastomeric polymer (a-1) may have a single layer structure or amulti-layer structure so long as the proportions of monomers of theelastomeric polymer as a whole fall within the above ranges.

As the alkyl methacrylate used in the graft component (a-2) arepreferred alkyl methacrylates having a C₁ to C₄ alkyl group, e.g.,methyl methacrylate, ethyl methacrylate, propyl methacrylate and butylmethacrylate. The alkyl methacrylates may be used alone or in admixturethereof. The alkyl group of the alkyl methacrylate may be linear or maybe branched, but if the number of carbon atoms thereof exceeds 4, thereaction rate becomes slow. The content of the alkyl methacryalte in thegraft component (a-2) is at least 50% by weight, preferably at least 60%by weight, more preferably at least 70% by weight. If the content of thealkyl methacrylate is less than 50% by weight, the solvent resistanceand transparency of films deteriorate.

The alkyl methacrylate may be used in combination with other vinylmonomers copolymerizable therewith. Examples of the other vinyl monomersare, for instance, an alkyl acrylate having a C₁ to C₁₂ alkyl group suchas methyl acrylate, ethyl acrylate, propyl acrylate or butyl acrylate, ahydroxyalkyl (meth)acrylate such as hydroxyethyl (meth)acrylate,glycidyl (meth)acrylate, an unsaturated carboxylic acid such as acrylicacid, methacrylic acid or crotonic acid, an aromatic vinyl compound suchas styrene, α-methylstyrene, o-, m- or p-methylstyrene or chlorostyrene,a vinyl cyanide compound such as acrylonitrile or methacrylonitrile, ahalogenated vinyl compound such as vinyl chloride or vinylidenechloride, and the like. Alkyl acrylates are preferable.

The graft component (a-2) which has been graft-polymerized onto theelastomeric polymer (a-1) may be in the form of a single layer or amulti-layer so long as the proportions of monomers of the graftcomponent as a whole fall within the above ranges.

The proportions of elstomeric polymer (a-1) and graft component (a-2)used in the acrylic resin (A) are, based on 100 parts by weight of thetotal of (a-1) and (a-2), from 5 to 85 parts by weight for the formerand from 95 to 15 parts by weight for the latter, preferably from 10 to80 parts by weight for the former and from 90 to 20 parts by weight forthe latter, more preferably from 20 to 65 parts by weight for the formerand from 80 to 35 parts by weight for the latter. If the amount of theelastomeric polymer (a-1) is less than 5 parts by weight, the impactresistance of films deteriorates, and if the amount of the elastomericpolymer (a-1) is more than 85 parts by weight, the elongation andtransparency of films deteriorate.

The particle size of the elastomeric polymer (a-1) is from 50 to 400 nm,preferably 100 to 350 nm, more preferably 150 to 300 nm. If the particlesize is less than 50 nm, the impact resistance of films deteriorates,and if it is more than 400 nm, the flex whitening resistance and surfaceproperty of films deteriorate.

The method for preparing the acrylic resin (A) used in the presentinvention is not particularly limited and, for instance, suspensionpolymerization method and emulsion polymerization method are adoptable.It is preferably to conduct the preparation by emulsion polymerizationmethod using monomers such as alkyl acrylate, alkyl methacrylate andpolyfunctional monomer which are copolymerizable with these monomers andhave at least two non-conjugated double bonds per a molecule. Forexample, according to an emulsion polymerization method, elastomericpolymer (a-1) is firstly prepared and graft component (a-2) is thenprepared in the same reaction system. The emulsion polymerization can beconducted in a usual manner.

In the above-mentioned emulsion polymerization method, usualpolymerization initiators, particularly polymerization initiatorscapable of generating a free radical, are used. Examples of suchpolymerization initiators are, for instance, an inorganic peroxide suchas potassium persulfate or sodium persulfate, an organic peroxide suchas cumene hydroperoxide or benzoyl peroxide, and the like. Further,oil-soluble initiators such as azobisisobutyronitrile can be used. Thesemay be used alone or in admixture thereof.

These polymerization initiators may be used, as a usual redox initiator,in combination with a reducing agent such as sodium sulfite, sodiumthiosulfate, sodium formaldehyde sulfoxylate, ascorbic acid or ferroussulfate.

Surface active agents used in the emulsion polymerization are notparticularly limited, and any of surface active agents used for usualemulsion polymerization can be used. Examples thereof are, for instance,an anionic surface active agent such as a sodium alkyl sulfate, a sodiumalkylbenzene sulfonate or sodium laurate, and a non-ionic surface activeagent such as a reaction product of an alkyl phenol and ethylene oxide.The surface active agents may be used alone or in admixture thereof.Further, a cationic surface active agent such as an alkylaminehydrochloride may be used as occasion demands.

From a polymer latex obtained by such copolymerization, a resin isseparated and recovered by conducting usual coagulation (for example,coagulation using a salt), washing with water, dehydration and drying,or by treatment such as spray drying or freeze drying.

In the present invention, crosslinked acrylic polymer (B) isincorporated as a matting agent into the acrylic resin (A). As thecrosslinked acrylic polymer (B) is used a crosslinked copolymer of analkyl acrylate and an allyl methacrylate, or a graft copolymer obtainedby polymerizing a monomer component containing 60 to 100% by weight ofan alkyl methacrylate in the presence of the crosslinked copolymermentioned above.

The crosslinked acrylic polymer (B) used as a matting agent in thepresent invention is preferably a copolymer comprising (b-1) 40 to 100parts by weight, preferably 50 to 90 parts by weight, of a crosslinkedacrylic ester copolymer having a single or multi layer structureprepared by polymerizing in one or more stages a monomer mixtureconsisting of an acrylic monomer composed of 40 to 90% by weight,preferably 50 to 85% by weight, more preferably 60 to 80% by weight, ofan alkyl acrylate and 60 to 10% by weight, preferably 50 to 15% byweight, more preferably 40 to 20% by weight, of an alkyl methacrylate, 0to 10% by weight of at least one other vinyl monomer copolymerizablewith the acrylic monomer (based on the total of the acrylic polymer andthe other vinyl monomer), and 0.1 to 20 parts by weight, preferably 0.5to 10 parts by weight, of a polyfunctional monomer having at least twonon-conjugated double bonds per a molecule and copolymerizable with theabove-mentioned monomers based on 100 parts by weight of the total ofthe acrylic monomer and the other vinyl monomer, and (b-2) 60 to 0 partby weight, preferably 50 to 10 parts by weight, of a graft componenthaving a single or multi-layer structure and composed of 60 to 100% byweight, preferably at least 70% by weight, of an alkyl methacrylate, 0to 40% by weight, preferably at most 30% by weight, of an alkyl acrylateand 0 to 10% by weight, preferably 0 to 5% by weight, of other vinylmonomer copolymerizable therewith which have been graft-copolymerizedonto the crosslinked acrylic ester polymer (b-1).

It is preferable that the crosslinked acrylic copolymer (B) has a weightaverage particle size of 0.5 to 15 μm, preferably 1 to 10 μm. If theweight average particle size of the crosslinked acrylic copolymer (B) isless than 0.5 μm, the matting effect lowers, and if it is more than 15μm, the impact resistance or the flex whitening resistance lowers.

If the amount of the alkyl acrylate in the acrylic monomer used in thecrosslinked acrylic ester polymer (b-1) is less than 40% by weight, theimpact resistance deteriorates, and if it is more than 90% by weight,the flex whitening resistance and transparency deteriorate. As the alkylacrylate and alkyl methacrylate used in the crosslinked acrylic esterpolymer (b-1) are exemplified those used for the acrylic resin (A).These may be used alone or in admixture thereof.

The acrylic monomer may be used in combination with other vinyl monomerscopolymerizable therewith. Examples of the copolymerizable other vinylmonomers are, for instance, an aromatic vinyl compound such as styrene,α-methylstyrene, o-, m- or p-methylstyrene or chlorostyrene, a vinylcyanide compound such as acrylonitrile or methacrylonitrile, anunsaturated carboxylic acid such as acrylic acid, methacrylic acid orcrotonic acid, a halogenated vinyl compound such as vinyl chloride orvinylidene chloride, and the like. These may be used alone or inadmixture thereof.

As the polyfunctional monomer having at least two non-conjugated doublebonds per a molecule used in the crosslinked acrylic ester polymer (b-1)are exemplified those used for the acrylic resin (A). These may be usedalone or in admixture thereof. If the amount of the polyfunctionalmonomer is less than 0.1 part by weight, the matting effect lowers, andif it is more than 20 parts by weight, the impact resistance of filmslowers.

The crosslinked acrylic ester polymer (b-1) may be used as a mattingagent as it is, or may be further subjected to graft polymerizationwherein a monomer component containing 60 to 100% by weight of an alkylmethacrylate is graft-polymerized onto the polymer (b-1) in one or morestages. If the amount of the crosslinked acrylic ester polymer (b-1) isless than 40 parts by weight per 100 parts by weight of the total of thepolymer (b-1) and the graft component (b-2), the matting effectdecreases.

If the content of the alkyl methacrylate in the monomer component (b-2)to be graft-polymerized onto the crosslinked acrylic ester polymer (b-1)is less than 60% by weight, the solvent resistance or the processabilitydeteriorates. As the alkyl acrylate and alkyl methacrylate used in themonomer component (b-2) to be graft-polymerized onto the crosslinkedacrylic ester polymer (b-1) are exemplified those used for the acrylicresin (A). These may be used alone or in admixture thereof.

Examples of the copolymerizable other vinyl monomers used in the graftcomponent (b-2) are, for instance, an aromatic vinyl compound such asstyrene, α-methylstyrene, o-, m- or p-methylstyrene or chlorostyrene, avinyl cyanide compound such as acrylonitrile or methacrylonitrile, anunsaturated carboxylic acid such as acrylic acid, methacrylic acid orcrotonic acid, a halogenated vinyl compound such as vinyl chloride orvinylidene chloride, and the like. These may be used alone or inadmixture thereof.

The method for preparing the crosslinked acrylic polymer (B) for mattingis not particularly limited, and it is prepared, for example, bysuspension polymerization method, emulsion polymerization method or thelike. From the viewpoint of obtaining the crosslinked acrylic polymer(B) having a weight average particle size of 0.5 to 15 μm, it ispreferable to prepare it by suspension polymerization, using an alkylacrylate, an alkyl methacrylate, a polyfunctional monomer and optionallyother ethylenically unsaturated monomers. From a polymer slurry obtainedby such copolymerization, the polymer (B) is separated and recovered byusual operations such as washing with water, dehydration, drying and thelike.

Thermoplastic resin composition (I) of the present invention is preparedby incorporating the crosslinked acrylic polymer (B) for matting intothe acrylic resin (A). The crosslinked acrylic polymer (B) is used in anamount of 0.5 to 20 parts by weight, preferably 1 to 15 parts by weight,more preferably 2 to 10 parts by weight, based on 100 parts by weight ofthe acrylic resin (A). If the amount of the polymer (B) is less than 0.5part by weight, the matting property is low, and if it is more than 20parts by weight, the processability, surface property or flex whiteningresistance of films deteriorates.

The preparation of the thermoplastic resin composition (I) is carriedout in a usual manner. For example, the preparation is carried out bysuch a method as mixing the components (A) and (B) by a mixer such as aHenschel mixer, and melt-kneading the resulting mixture by an extruder,a roll mill or the like.

The thermoplastic resin composition (I) of the present invention isuseful particularly for films. For example, films which have a goodprocessability of high stretching and excellent impact resistance,transparency, weatherability, solvent resistance and flex whiteningresistance and are improved in printing defect, are obtained by a usualmelt extrusion method such as inflation method or T-die extrusionmethod, a calendering method, a solution casting method, or the like. Itis appropriate that the thickness of the films is from 10 to 300 μm, anda thickness of 15 to 200 μm is preferable.

The resin composition of the present invention may one or more of usualadditives, such as inorganic or organic pigment or dye for pigmentation,antioxidant to enhance the stability to heat and light, ultravioletabsorber, light stabilizer and the like.

In the present invention, formation of the thermoplastic resincomposition (I) into films is carried out in such a manner that, whenapplying a high stretching processing to a film, the both surfaces ofthe film are simultaneously brought into contact with rolls havingdifferent temperatures during the time when the film temperature is notless than Tg of the thermoplastic resin (I), that is, one surface of thefilm is brought into contact with a roll having a temperature of notless than Tg, preferably not less than Tg+10° C., and the other surfaceof the film is brought into contact with a roll having a temperature ofless than Tg, preferably Tg−10° C., whereby matt acrylic films having anexcellent printability are obtained. If the temperature of the rollcontacted with the surface to be made smooth is less than Tg, the effectof making the film surface smooth is insufficient. If the temperature ofthe roll contacted with the surface to be delustered is more than Tg,the effect of delustering the film surface is not obtained. Thetemperature of the film when pressed by rolls is not less than Tg,preferably not less than Tg+10° C., more preferably not less than Tg+20°C., the most preferably not less than Tg+30° C. If the film temperatureis less than Tg, the effect of making the film surface smooth isinsufficient. It is preferable that the film temperature is not morethan Tg+100° C., since the influence of heat becomes too large if thetemperature is too high. The material of the rolls are not particularlylimited and includes, for instance, metals and rubbers.

In order to prevent the printing defect from occurring as much aspossible by decreasing protrusions on the film surface, it is desired,for example, that the number of protrusions such as fish eye on the filmsurface is at most 5 per m², preferably at most 3 per m², morepreferably at most 2 per m² and the most preferably at most 1 per m².

The present invention is more specifically explained by means of thefollowing examples and comparative examples in which all parts and % areby weight unless otherwise noted. It is to be understood that thepresent invention is not limited to these examples.

In the examples and comparative examples, measurement and evaluationwere made according to the following conditions and methods.

(1) Glass Transition Temperature (Tg)

Tg was measured according to JIS K 7121 by using a differential scanningcalorimeter (DSC) made by Seiko Denshi Kogyo Kabushiki Kaisha.

(2) Melt Index

The measurement was made at 230° C. under a load of 5 kg.

(3) Impact Resistance

A 50 μm thick film was laminated onto a polycarbonate sheet (thickness0.8 mm), and a falling ball impact test of the laminate was made at −20°C. according to JIS K 5400. The energy was calculated by the equation:(50% failure height)×(weight of ball). The unit is J joule).

(4) Gloss

Using a gloss meter made by Nippon Denshoku Kogyo Kabushiki Kaisha, 60°light reflectance of the film surface contacted with a lower temperatureroll was measured at 23° C. according to JIS Z 8741. The unit is %.

Further, in order to evaluate the change in gloss (change in degree ofmatting) by heat treatment, a sample film having a size of 100 mm×100 mmwas fixed by an aluminum frame, kept in an oven at 200° C. for 60seconds and cooled, and the reflectance (gloss) (%) after heating at200° C. for 1 minute was measured by the gloss meter mentioned aboveaccording to JIS Z 8741.

(5) Solvent Resistance

A 50 μm thick film was cut into a strip having a width of 10 mm and alength of 100 mm, and was immersed in toluene with suspending a 2.3 gweight to the strip. The time until the strip was broken was measured.The unit is second.

(6) Flex Whitening Resistance

A 50 μm thick film was folded up 180°, and the whitening resistance wasevaluated according to the following criteria.

-   ∘: No whitening is observed at the fold.-   Δ: The fold is slightly whitened.-   X: Whitening is observed at the fold.    (7) Processability

A resin composition was extruded by a T-die extrusion method into a filmhaving a thickness of 50 μm, and the processability was evaluatedaccording to the following criteria.

-   ∘: Composition can be stably extruded to a film having a uniform    thickness without breaking of the film.-   Δ: Breaking of film does not occur, but the film thickness is    slightly uneven and stable extrusion cannot be conducted.-   X: Breaking of film occurs, and the extrusion is unstable.    (8) Printing Defect

Gravure printing was applied to the mirror surface of a film, andprinted film having a width of 1 m and a length of about 10 m wasvisually checked to count the number of non-printed spots. The number ofnon-printed spots per 1 m² is shown.

(9) Ink Receptivity

Gravure printing was applied to the mirror surface of a film, and theink receptivity was visually evaluated with respect to printed filmhaving a width of 1 m and a length of 1 m according to the followingcriteria.

-   ∘: Print is sharp.-   Δ: Print is slightly unclear.-   X: Print is unclear.    (10) Surface Property

The surface appearance of a film was visually observed and evaluatedaccording to the following criteria.

-   ∘: Burning and foreign matter are scarcely observed.-   Δ: Burning and foreign matter are slightly observed.-   X: Either burning or foreign matter is observed, and the surface is    uneven.

The abbreviations described hereinafter denote the following compounds.

-   OSA: Sodium dioctyl sulfosuccinate-   BA: Butyl acrylate-   MMA: Methyl methacrylate-   ST: Styrene-   CHP: Cumene hydroperoxide-   AMA: Allyl methacrylate-   tDM: Tertiary-dodecylmercaptan-   BDMA: 1,4-Butylene glycol dimethacrylate-   BPO: Benzoyl peroxide

EXAMPLES 1 TO 8 AND COMPARATIVE EXAMPLES 1 TO 3

(1) Preparation of Acrylic Resin (A) (A-1 to A-4)

An 8 liter polymerization reactor equipped with a stirrer, athermometer, a nitrogen gas feeding tube, a monomer feeding tube and areflux condenser was charged with the following materials, and sodiumdioctyl sulfosuccinate (OSA) in an amount shown in Table 1.

Water 200 parts Sodium formaldehyde sulfoxylate 0.15 part Ferroussulfate dihyrate 0.0015 part Disodium ethylenediaminetetraacetate 0.006part

After purging the reactor with nitrogen gas, the inner temperature waselevated to 60° C., and a mixture (1) shown in Table 1 was continuouslyadded to the reactor at a rate of 15 parts/hour to conductpolymerization. After the completion of the addition, the polymerizationwas further continued for 1 hour to give an elastomeric polymer (a-1) ina polymerization conversion of at least 98%.

In the presence of the elastomeric polymer (a-1), a monomer mixture (2)shown in Table 1 was then polymerized as a graft component (a-2) bycontinuously adding it to the reactor at a rate of 10 parts/hour. Thepolymerization was further continued for 1 hour to raise thepolymerization conversion to 98% or more, thus giving a latex of anacrylic resin (A).

The obtained latex was salted out with calcium chloride, washed withwater and dried to give a dry powder of acrylic resin (A).

TABLE 1 Acrylic resin (A) A-1 A-2 A-3 A-4 OSA (part) 0.25 0.05 0.0050.001 Mixture (1) (part) 30 35 15 4 (elastomeric polymer a-1) MMA (%) 105 20 70 BA (%) 90 95 80 30 AMA (part) 0.40 0.30 0.05 0.001 CHP (part)0.02 0.03 0.02 0.005 Mixture (2) (part) 70 65 85 96 (graft componenta-2) MMA (%) 90 85 30 60 BA (%) 10 15 70 40 tDM (part) 0.20 0.15 — 0.25CHP (part) 0.30 0.35 0.40 0.22 Weight average particle size (nm) 85 300600 120 of elastomeric polymer (a-1)(2) Preparation of Crosslinked Acrylic Polymer (B) Used for Matting (B-1to B-5)

An 8 liter polymerization reactor equipped with a stirrer, athermometer, a nitrogen gas feeding tube, a monomer feeding tube and areflux condenser was charged with the following materials.

Water  200 parts Sodium lauryl sulfate 0.05 part Sodium polyacrylate0.55 part Sodium sulfate  1.6 parts

After purging the reactor with nitrogen gas, the inner temperature waselevated to 60° C., and a mixture (1) shown in Table 2 was added to thereactor. The polymerization was conducted up to a polymerizationconversion of at least 98% to give a crosslinked acrylic ester polymer(b-1).

In the presence of the crosslinked acrylic ester polymer (b-1), amonomer mixture (2) shown in Table 2 was then polymerized as a graftcomponent (b-2) by continuously adding it to the reactor at a rate of 15parts/hour. After the completion of the addition, the polymerization wasfurther continued up to a polymerization conversion to 98% or more togive a slurry of a crosslinked acrylic polymer (B) used for matting.

The obtained slurry was washed with water, dehydrated and dried to givea dry powder of crosslinked acrylic polymer (B).

TABLE 2 Crosslinked acrylic polymer (B) B-1 B-2 B-3 B-4 B-5 Mixture (1)(part) 60 85 100 30 65 (crosslinked acrylic ester polymer b-1) MMA (%)30 15 10 5 9 BA (%) 70 85 90 95 91 BDMA (part) 0.70 2.00 0.45 0.55 0.05BPO (part) 0.02 0.04 0.02 0.01 0.04 Mixture (2) (part) 40 15 — 70 35(graft component b-2) MMA (%) 90 95 — 70 55 BA (%) 10 5 — 30 45 BPO(part) 0.03 0.02 — 0.05 0.03 Weight average particle 5 3 6 8 20 size(μm) of crosslinked acrylic polymer (B)(3) Preparation of Thermoplastic Resin Composition (I)

Acrylic resin (A) and crosslinked acrylic polymer (B), which were shownin Table 3, were mixed by a Henschel mixer. The resulting mixture wasextruded at 190° C. by a vent-type extruder to pelletize, and thepellets were used for measurement and evaluation of properties. Theresidual monomer content of the pellets was not more than 500 ppm. Thepellets were extruded by an extruder having a T-die, and the extrudedfilm was brought into contact with rolls kept at temperatures shown inTable 3 when the film temperature had reached 170° C. The properties ofthe film were measured and evaluated.

The results are shown in Table 3.

TABLE 3 Example Com. Ex. 1 2 3 4 5 6 7 8 1 2 3 Acrylic resin (A) (partby wt.) A-1 100 — 100 100 — 100 100 — — — 100 A-2 — 100 — — 100 — — —100 — — A-3 — — — — — — — 100 — — — A-4 — — — — — — — — — 100 —Crosslinked acrylic polymer (B) (part by wt.) B-1 6 10 — — — — — — 55 —10 B-2 — — 6 — 8 — — — — — — B-3 — — — 10 — — — — — 10 — B-4 — — — — — 6— 15 — — — B-5 — — — — — — 10 — — — — Grass transition temperature ofresin 92 85 88 82 86 84 78 65 95 102 85 composition (° C.) Temperatureof one roll (° C.) 100 90 100 90 90 90 90 75 100 40 100 Temperature ofthe other roll (° C.) 60 40 50 60 50 50 50 40 40 40 100 Melt index ofresin composition 7.5 6.0 5.5 4.0 5.2 8.0 6.9 5.4 2.0 4.4 6.0 Impactresistance 11.1 9.8 8.6 15.3 9.4 2.5 3.2 2.1 1.8 0.2 9.8 Gloss 25 20 2720 24 35 55 15 18 18 80 Gloss after heating at 200° C. for 1 min. 30 2330 24 28 40 60 19 23 20 60 Solvent resistance 40 45 38 32 33 45 15 31 3928 45 Flex whitening resistance ∘ ∘ ∘ ∘ ∘ Δ Δ Δ x ∘ ∘ Processability ∘ ∘∘ ∘ ∘ ∘ Δ Δ x ∘ ∘ Printing defect 0 0 0.1 0.2 0 0.1 5.8 0.5 0.6 0.2 0Ink receptivity ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ x ∘ Surface property ∘ ∘ ∘ ∘ ∘ ∘ Δ Δ x∘ ∘

INDUSTRIAL APPLICABILITY

The acrylic matt thermoplastic resin film of the present invention hasexcellent properties such as flex whitening resistance, impactresistance and solvent resistance, and also has excellent surfaceproperty and good printability because of decreased number ofprotrusions such as fish eyes on the film surface and, moreover, can besecondarily processed with maintaining the matted state.

1. An acrylic matt thermoplastic resin film having a mirror surface onone side and a matt surface on the other side, and comprising an acrylicresin (A) and 0.5 to 20 parts by weight of a crosslinked acrylic polymer(B) as a matting agent based on 100 parts by weight of said acrylicresin (A).
 2. The film of claim 1, wherein said film has a thickness of10 to 300 μm.
 3. The film of claim 1, wherein said acrylic resin (A) isan acrylic graft copolymer comprising (a-1) 5 to 85 parts by weight ofan elastomeric polymer composed of 50 to 99.9% by weight of an alkylacrylate, 0 to 49.9% by weight of other copolymerizable vinyl monomerand 0.1 to 10% by weight of a copolymerizable polyfunctional monomerhaving at least two non-conjugated double bonds per a molecule, and(a-2) 95 to 15 parts by weight of a graft component composed of 50 to100% by weight of an alkyl methacrylate and 0 to 50 % by weight of othervinyl monomer copolymerizable therewith which have beengraft-polymerized onto said elastomeric polymer (a-1), in which saidelastomeric polymer (a-1) has a particle size of 50 to 400 nm.
 4. Thefilm of claim 1, wherein said crosslinked acrylic polymer (B) is acopolymer comprising (b-1) 40 to 100 parts by weight of a crosslinkedacrylic ester polymer prepared by polymerizing 100 to 90% by weight ofan acrylic monomer composed of 40 to 90% by weight of an alkyl acrylateand 60 to 10% by weight of an alkyl methacrylate with 0 to 10% by weightof at least one other copolymerizable vinyl monomer and 0.1 to 20 partsby weight of a copolymerizable polyfunctional monomer having at leasttwo non-conjugated double bonds per a molecule based on 100 parts byweight of the total of said acrylic monomer and said other vinylmonomer, and (b-2) 60 to 0 part by weight of a graft component composedof 60 to 100% by weight of an alkyl methacrylate, 0 to 40% by weight ofan alkyl acrylate and 0 to 10% by weight of other copolymerizable vinylmonomer which have been graft-polymerized onto said crosslinked acrylicester polymer (b-1).
 5. The film of claim 1, wherein said mirror surfacehas a print.
 6. The film of claim 1, wherein said film has a thicknessof 10 to 300 μm, and said acrylic resin (A) is an acrylic graftcopolymer comprising (a-1) 5 to 85 parts by weight of an elastomericpolymer composed of 50 to 99.9% by weight of an alkyl acrylate, 0 to49.9% by weight of other copolymerizable vinyl monomer and 0.1 to 10% byweight of a copolymerizable polyfunctional monomer having at least twonon-conjugated double bonds per a molecule, and (a-2) 95 to 15 parts byweight of a graft component composed of 50 to 100% by weight of an alkylmethacrylate and 0 to 50% by weight of other vinyl monomercopolymerizable therewith which have been graft-polymerized onto saidelastomeric polymer (a-1), in which said elastomeric polymer (a-1) has aparticle size of 50 to 400 nm.
 7. The film of claim 1, wherein said filmhas a thickness of 10 to 300 μm, and said crosslinked acrylic polymer(B) is a copolymer comprising (b-1) 40 to 100 parts by weight of acrosslinked acrylic ester polymer prepared by polymerizing 100 to 90% byweight of an acrylic monomer composed of 40 to 90% by weight of an alkylacrylate and 60 to 10 % by weight of an alkyl methacrylate with 0 to 10%by weight of at least one other copolymerizable vinyl monomer and 0.1 to20 parts by weight of a copolymerizable polyfunctional monomer having atleast two nonconjugated double bonds per a molecule based on 100 partsby weight of the total of said acrylic monomer and said other vinylmonomer, and (b-2) 60 to 0 part by weight of a graft component composedof 60 to 100% by weight of an alkyl methacrylate, 0 to 40% by weight ofan alkyl acrylate and 0 to 10% by weight of other copolymerizable vinylmonomer which have been graft-polymerized onto said crosslinked acrylicester polymer (b-1).
 8. The film of claim 5, wherein said acrylic resin(A) is an acrylic graft copolymer comprising (a-1) 5 to 85 parts byweight of an elastomeric polymer composed of 50 to 99.9% by weight of analkyl acrylate, 0 to 49.9% by weight of other copolymerizable vinylmonomer and 0.1 to 10% by weight of a copolymerizable polyfunctionalmonomer having at least two non-conjugated double bonds per a molecule,and (a-2) 95 to 15 parts by weight of a graft component composed of 50to 100% by weight of an alkyl methacrylate and 0 to 50% by weight ofother vinyl monomer copolymerizable therewith which have beengraft-polymerized onto said elastomeric polymer (a-1), in which saidelastomeric polymer (a-1) has a particle size of 50 to 400 nm, and saidcrosslinked acrylic polymer (B) is a copolymer comprising (b-1) 40 to100 parts by weight of a crosslinked acrylic ester polymer prepared bypolymerizing 100 to 90% by weight of an acrylic monomer composed of 40to 90% by weight of an alkyl acrylate and 60 to 10% by weight of analkyl methacrylate with 0 to 10% by weight of at least one othercopolymerizable vinyl monomer and 0.1 to 20 parts by weight of acopolymerizable polyfunctional monomer having at least twonon-conjugated double bonds per a molecule based on 100 parts by weightof the total of said acrylic monomer and said other vinyl monomer, and(b-2) 60 to 0 part by weight of a graft component composed of 60 to 100%by weight of an alkyl methacrylate, 0 to 40% by weight of an alkylacrylate and 0 to 10% by weight of other copolymerizable vinyl monomerwhich have been graft-polymerized onto said crosslinked acrylic esterpolymer (b-1).
 9. The film of claim 1, wherein said film has a thicknessof 10 to 300 μm, said acrylic resin (A) is an acrylic graft copolymercomprising (a-1) 5 to 85 parts by weight of an elastomeric polymercomposed of 50 to 99.9% by weight of an alkyl acrylate, 0 to 49.9% byweight of other copolymerizable vinyl monomer and 0.1 to 10% by weightof a copolymerizable polyfunctional monomer having at least twonon-conjugated double bonds per a molecule, and (a-2) 95 to 15 parts byweight of a graft component composed of 50 to 100% by weight of an alkylmethacrylate and 0 to 50% by weight of other vinyl monomercopolymerizable therewith which have been graft-polymerized onto saidelastomeric polymer (a-1), in which said elastomeric polymer (a-1) has aparticle size of 50 to 400 nm, and said crosslinked acrylic polymer (B)is a copolymer comprising (b-1) 40 to 100 parts by weight of acrosslinked acrylic ester polymer prepared by polymerizing 100 to 90% byweight of an acrylic monomer composed of 40 to 90% by weight of an alkylacrylate and 60 to 10% by weight of an alkyl methacrylate with 0 to 10%by weight of at least one other copolymerizable vinyl monomer and 0.1 to20 parts by weight of a copolymerizable polyfunctional monomer having atleast two non-conjugated double bonds per a molecule based on 100 partsby weight of the total of said acrylic monomer and said other vinylmonomer, and (b-2) 60 to 0 part by weight of a graft component composedof 60 to 100% by weight of an alkyl methacrylate, 0 to 40% by weight ofan alkyl acrylate and 0 to 10% by weight of other copolymerizable vinylmonomer which have been graft-polymerized onto said crosslinked acrylicester polymer (b-1).
 10. The film of claim 2, which has a print on themirror surface.
 11. The film of claim 3, which has a print on the mirrorsurface.
 12. The film of claim 4, which has a print on the mirrorsurface.
 13. The film of claim 6, which has a print on the mirrorsurface.
 14. The film of claim 7, which has a print on the mirrorsurface.
 15. The film of claim 8, which has a print on the mirrorsurface.
 16. The film of claim 9, which has a print on the mirrorsurface.